The deprecated model_base mixins are be being removed from neutron/db/model_base.py and neutron/db/models_v2.py in [1]. The mixins from neutron_lib.db.model_base should be used instead. All subproject maintainers should update their code to use the model_base mixins from neutron-lib. I have submitted patches [2] for the stragglers that I found. [1] https://review.openstack.org/403329 [2] https://review.openstack.org/#/q/status:open+topic:use-lib-model_base